#include<stdio.h>
#include<conio.h>

 int main()
 
{
    int a,b;
    
	printf("nhap a, b:");
	scanf("%d%d",&a, &b);
    while(a!=b)
	{
		if(a>b)
	    a=a-b;
		else
		b=b-a;
		}
	printf("\n UCLN la: %d",a);
	getch();
}
